Circuit breaker



Dec. 2, 1958 D. B. POWELL 2,863,022

CIRCUIT BREAKER Filed April .20, 1955 INVENTOR. DAVID B. POWELL iqwm'wATTORNEY Unite States Patent CIRCUIT BREAKER David B. Powell, Bristol,Conn., assignor to General Electn'c Company, a corporation of New YorkApplication April 20, 1955, Serial No. 502,693

13 Claims. (Cl. 200-116) My invention relates to automatic electriccircuit breakers and, more particularly, to small air circuit breakersof the type used for the control and protection of light and powerbranch circuits in residential and industrial electrical systems.

One object of my invention is to provide a circuit breaker having aquick make and quick break action, that is, one in which opening andclosing movement of the movable contact is not dependent on the speed ofmovement of the operating handle.

Another object is to provide a circuit breaker having separablebutt-type contacts which have a sliding or wiping action beforeseparation and after closing to improve the electrical contact andremove surface impurities.

A general object of my invention is to provide such a circuit breakerwhich is small, compact, simple in construction and assembly, andinexpensive to manufacture.

Another object of my invention is to provide such a circuit breakerwhich is simple for the user to operate.

Another object of my invention is to provide such a circuit breakerwhich indicates its automatically tripped condition by movement of itshandle automatically to the off position.

Further objects of my invention will become apparent to those skilled inthe art as the following detailed description proceeds.

My invention will be readily understood from the following detaileddescription taken in connection with the accompanying drawing and itsscope willbe pointed out in the appended claims.

Figure 1 is a side elevation view of a circuit breaker made inaccordance with my invention, the parts being shown in the normal on orclosed-circuit position.

Figure 2 is a sectional view of the circuit breaker of y Figure 1 takenon the lines 2-2 of Figure 1.

Figure 3 is a side elevation view of the circuit breaker of Figure 1,the parts being shown in the off or opencircuit position.

Figure 4 is a side elevation view on reduced scale of the circuitbreaker of Figure 1, the parts being shown in an intermediate positionwhich they assume when the handle is moved inwardly from the on positionof Figure 1.

Figure 5 is a side elevation view of the casing of the circuit breakerof Figure 1, the parts being removed.

Figures 6a and 6b are side and end views, respectively, of the manuallyoperable handle of the circuit breaker.

In the drawing I have shown my invention as embodied in a circuitbreaker comprising a generally rectangular open-sided insulating casing10 adapted to be closedby a suitable side cover 11 which may be retainedby suitable means such as by screws or rivets passing through theopenings 12.

For the purpose of connecting the circuit breaker to a circuit to becontrolled and protected, I provide a load terminal 13 and line terminal14. The load terice minal 13 is adapted to be connected to a wire whichmay be inserted under the head of the screw 13a. The line terminal 14 isadapted to be connected to a source of power by frictional engagementwith a suitable stationary connector (not shown) at the surface 14a.

The line terminal 14, comprising a generally L-shaped strap, has one.end portion 14b resting against an abutment 10a of the casing 10, anintermediate portion extending around the pin 15 in the casing 10, andan elongated portion 14d resting at one point against an abutment 10b inthe casing 10. An elongated bimetallic strip 16 is rigidly attached tothe other end of the terminal member 14 by suitable means such as bywelding. A calibrating screw 17 is threadedly engaged in the united endportions of the bimetallic strip 16 and the terminal strip 14. The innerend of the calibrating screw 17 bears against an abutment in the casing10 and the opposite end is accessible for adjustment from outside thecasing 10 through opening 17a. Inward turning of the calibration screw17 bends the end of the terminal strip 14 downwardly over the abutment10b, altering the position of the free. end of the bimetallic strip topermit adjustment or calibration. strip 16 has a flexible braid 19attached thereto by suitable means such as by brazing, and the other endof the braid 19 is similarly attached to one end of the elongatedcontact arm 20 adjacent the movable contact member 21. The movablecontact member 21 is adapted to cooperate with a relatively stationarycontact 22 mounted on the load terminal 13.

The electrical circuit through the circuit breaker when in the closedposition as, for instance, in Figure 1, may therefore be traced asfollows: From the source of power (not shown) to the contact surface 14aof line terminal 14, to one end of the bimetallic arm 16, to the braid19, to the contact arm 20, to the movable contact 21, to the relativelystationary contact 22, to the load terminal 13, and thence to the load(not shown).

For the purpose of aiding in the extinction of the are formed uponseparation of the contacts, I provide an arcing chamber generallyindicated at 45 provided with vent portions 46 having fins 4-7therebetween, preferably integral with the casing 10.

The movable contact arm 20 has one end thereof adapted to be releasablyrestrained by means of a latch member 23. The latch member 23 ispivotally supported in the circuit breaker casing 10 by means ofcylindrical lugs 24 and has a first portion 25 provided with an aperture26 ,and an adjacent ledge 26' on which the end of the bimetallic strip16 is adapted normally to latch. The bimetallic strip 16 has its highexpansion side adjacent the bottom wall of the breaker. Its free endtherefore deflects upwardly upon heating so as to move into the aperture26, permitting slight rotation of the latch 23 (clockwise as viewed) tothe dotted line position of Figure 3. The latch 23 has a second portion27 adapted to engage the bent-up end portion 28 of the movable contactarm 20 and to restrain it in the on" or closedcircuit position as shownin Figure 1. Latch 23 is provided with a further projection or tongue44, adapted to be engaged by the corner 28' of the contact member 20 inthe process of resetting the circuit breaker, in a manner to bedescribed. The latch 23 is preferably made of one integral piece fromwhich the portions 25, 27, 44 and pivot lugs 24'are formed. The tongue44, for instance, is preferably formed by lancing out a piece from theportion 25, as shown.

When the bimetal deflects and moves off the ledge 26', the latch 23rotates clockwise under the bias of contact arm 20 and the end 28 isreleased from latch surface 27. For the purpose of preventinglongitudinal movement of Patented Dec. 2, 1958" The movable end of thebimetallic Z2 thexcontact 8.1111129 prior to release of the end 28 fromthe latch surface 27, I provide a stop pin ,33 against which the end 28of the contact arm 20 is adapted normally to bear.

Amain operating;tensionspring 29 has'one end hooked in; an apertured.portion 30 generally centrally of the contact arm: 20 and, the: otherendanchoredtoa fixed: In. the on position. of

inner sidewalls provided with an irregularly shaped recess 32(see'Figure 5) and the contact arm20hasxa transversely extendingpin 20arigidly attached thereto by suitable meanssuch as by welding. The pin 2%.has'

its opposite endsprojecting beyond the sides of-the:con= tact memberzt)and into the recesses 32, so that at cer taintimes the pin 20a has itsmovements limited by walls' ofthe recesses 32. In addition, the portionsof. pin 2041' projecting beyondthe contact arm Ztl but intermediate thecontact arm 20 and the extreme ends just mentioned which extend into therecesses 32, are adapted to serve.

as operating abutment portions for thecontactarm 20, and to cooperatewith the abutments 4t and thecamzsur faces 39 of the handle 34 in amanner to be described.

Upon deflection of the bimetal 16 and consequent auto-#- matic releaseof the end 28 of the contact arm 20, the tension spring 29 moves the arm29 upwardly and to the right until the pin 20a rests in the corner 32aof the recesses32. The spring then rotates the contact arm 20 in acounterclockwise direction about the pin 20a as a pivot, causing themovable contact 21 to move, away from the stationary contact 22.

The handle -is biased outwardly by spring 41, and its outward travel islimited by the engagement of bridgingportion 38with the underside of thecontact arm 20.

when the parts are in the position as shown in Figure 3. For the purposeof resetting the contact arm 20 to the relatched and reclosed position,and also for the purpose of manually operating the contact arm 20 to theopenv and close. position, I provide a handle member 34 comprising agenerally rectangular elongated push rod of insulating material which isslidably supported for reciprocating straight-line movement in thecasing by the casing walls and by sides of the bosses. lltlc, d and110s. Thehandle member 34 is provided with an outwardly accessible.manually operable portion 35 having a marking ring 36 thereon,preferably of contrasting color. The centralpart of the lower portion ofthe handle 34 is cut away to provide two generally parallel spaced-apartside wall portions 37a and 37b, joinedat their outer extremities by abridging portion 38; The side wall portions 3761,.and 3712 are providedwith cam surfaces 39 and operatingshoulders 4th for, a purpose to bedescribed.

The -handle 3.4 is biased upwardly at all times by'a:biasingspring41'having its body portion encircling the pin 31.and;having oneend'resting against an inner wall, of

the casing ltlandits other end resting against an abut-- ment42.intermediate the side walls 37a andv37b of the handle 34.

With: the .parts in the openposition as indicated in Figure 3, themovement of the handle member '34 outwardly underthe bias of the spring41 is limited by the bridging, portion: 38 which underlies contact arm2% When in this position, the marking ring 36 is visible above they-topwall of the-breaker, indicating that the circuit breaker, is in the offor open position. It will be observed that in this position, theshoulders 40 directly overlie the ends of the pin a although a smallamount of vclearance exists .therebetween. In order to reclose thecircuit breaker, thehandle member 34 is pushed inwardly,

causing-the shoulders 40 to engage the ends of the pin- 2tia,:,movingitinadownwardly direction, the pin,.2tla

the.corners..,formed..by the junctureof shoulder portionv 40 and thevertical portion 48. As downward movement is continued, the forward end20b of the contact member 20, adjacent the movable contact 21, strikesan abutment 4-3 in the casing 10. Further downward movement of thehandle 34 thereafter causes the forward end 2% of the contact arm 2t toslideagainst the abutment 43 and the opposite end 28 of arm 20 torotatedownwardly in a clockwise direction. As this occurs, the curvedportion 28 of the contact arm ZtLengages the bent-over portion 27 of thelatch 23 or-the pin 33 (if latch 23 is not in latched engagementwithgthe endof bimetal 16) and acts as a cam, forcing the contact member20 to slide slightly, longitudinally, to the left until restricted bysurface 320 of one of the walls of the recess 32 in the casing 1d. Thelast portion of downward movement of handle member 34 then causes thecorner 28 to engage a tongue 44cm the latch member-23 rotating the latchmember 23 slightly in a counterclockwise direction against the'innersurface-of portion 141: of the strip Has a stop, and permittingthebirnetal-lic strip into spring to its 'normal'or latched position(assuming that ithas cooled sufiiciently) and-causing the latching end27 of the latch 23 to again overlie the end 28 of the'contact member 20.

As the -handle 34 is thereafter-released, the main ten* sion spring 29,pulling upwardly and to the right on the intermediate portion of thecontact arm 20, biases the end 28of the contact arm 26* against the stoppin 33 in a horizontal direction, and upwardly against the undersideoflatchsurface-27 in a vertical direction, tending thereby to rotate thelatch 23in a clockwise direction. Such clockwise movement of latch 23 isprevented, however, by the engagement of the end of bimetal 16 withthe-shelf 26 of the portion 25. The net effect of the pull of'springtherefore is torotate the contactarm-as a whole about the end'28 as theshoulders 40 permit the pinlda to move upwardly. As this rotation takesplace, it will be observed that'the'path ofmotion of the pin-Zi a isalong an are centered about the tip of latch 23 and being such as tomove the pin Ztla to the left aswell as up wardly. Shortly before themovable contact 21 reaches its final or full on position, the ends ofthe pin 2% slide off the ends-of the sh0ulders'40, and'the contactsclose with a snap action even though the handle is slowly released.

The above description has set forth the automatic opening or"trippingaction of'the breaker in going from Figure 1 to Figure 3, and theresetting and reclosing action inreturning from Figure'3 to-Figure 1.The manually operated opening actionand closing action by meansof'theoperating member 34 will now be described.

When'theparts are in the closed-circuitposition of Figure 1 and themanually operable handle 34 is depressed, the pin20abeing'intheleft-hand portion of the recesses 32, is not'engaged bythe shoulders' ttb. Instead;

it is engaged by the cam surfaces 39 on the side portions" member 20 outof engagement with the latch surface 27 of the latch'23. Upon release ofthe latch portion 2 5 from'latch 23', the tension spring 29 is free torotate the contact arm 20 counterclockwise to separate the contacts Hand22 with a snap action'independent of the speed of the handle the contactarm going to the position of Figure 4. At the instant of such openingaction, the pin 20:; is in contact with the cam surfaces 39 as indicated .in. Figure 4, and it remains there so long as the handle isheld inwardly. Upon subsequent release of the handle 34, thehandleismoved to an upward position by the .handle-returnvspring, while at thesame time the tension Spring- 29 tends, to move the contact arm2011poccurrence of overload conditions.

. ward and to the right. As a consequence, the end of the pin a slidesoff the cam surfaces 39 and moves into the corner 32a of the recesses32. The parts, therefore, have returned to the position indicated inFigure 3, from which position latching and reclosing is accomplished inthe manner described above.

It will be observed that both opening and closing movements of thecontacts of my improved circuit breaker take place with a snap actionirrespective of the speed of the movement of the manually operablemember. It will be seen, moreover, that the handle need be operated onlyin a reciprocating manner and only a pushing movement on the handle isrequired to open the breaker or to close it, even after automaticopening. Furthermore, the open condition of the circuit breaker isclearly indicated by the signal band 36 on the handle 34, the handlebeing further outward upon opening of the contacts than it is when thecontacts are closed, due to the difference in position of theintermediate portion of contact member 2t), which portion acts as a stopfor the handle 34. It w1ll be noted, furthermore, that the trippingaction takes place irrespective of the maintenance of the handle in theclosed circuit position or, in other words, the circuit breaker is tripfree.

It is pointed out that although manual opening is accomplished byreleasing of a latch engagement, this latch engagement is not the samelatch engagement as the trip latch which is automatically released uponthe Thus, manual opening of the circuit breaker, even a great number oftimes, does not cause wear of the trip latching surfaces and thereforethe accurate calibration of the circuit breaker is not adverselyaffected.

By the arrangement of bimetal 16 and terminal strap 14, the action ofthe bimetal is accelerated on very high overloads by a magneticrepulsion between the bimetal 16 and the adjacent portion 14d of theterminal 14, since the current in these members travels in oppositedirections. This magnetic tripping action is sufficient to causetripping completely unaided on very high short-circuits, and it assistsor cooperates with the deflecting action of the birnetal on mediumoverloads.

It will also be seen that I have provided a circuit breaker which may beused as an alternate action switch wherein a complete cycle of movementof the handle to depressed and released condition results in onlyone-half cycle movement of the contact member, i. e., from closed toopen position or vice versa.

Since many modifications may be made in the form and arrangement ofparts of my invention without departing from the scope thereof, I do notwish to be limited to the specific form and arrangement shown, butcontemplate rather by the appended claims to cover all suchmodifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. An electric circuit breaker comprising a manually operable memberhaving a cam surface and an operating surface and being movable back andforth along a predetermined path, a latch, a movable contact memberhaving a latched position in which a portion thereof is in engagementwith and restrained by said latch and a tripped position in which saidportion thereof is out of engagement with said latch, said contactmember having a portion located in the path of movement of said camsurface when said contact member is in said latched position wherebymovement of said manually operable member along said path in a firstdirection when said contact member is in said latched position causessaid cam surface to engage said portion of said contact member and todisengage said contact member from said latch, and said contact memberhaving a portion located in the path of movement of said operatingsurface when said contact member is in said tripped position wherebymovement 6 of said manually operable member along said path in saidfirst direction when said contact member is in said tripped positioncauses said operating surface to engage said portion of said operatingmember and to reengage it with said latch.

2. An electric circuit breaker as set forth in claim 1 said circuitbreaker also comprising a latch movable with respect to the contactmember, means biasing said latch in a releasing direction, and currentresponsive means for causing movement of said latch to said releasedposition upon the occurrence of predetermined electrical conditions insaid circuit breaker.

3. An electric circuit breaker comprising a manually operable memberhaving a cam surface and an operating surface, means mounting saidmanually operable member for reciprocating straight-line movement alonga predetermined path, said cam surface and said operating surfacedescribing paths of movement different from each other when saidoperating member is moved along said predetermined path, a movablecontact arm having an operating abutment, a latch, said contact armhaving a latched position in which it is in engagement with said latch,means for moving said contact arm and said latch relative to each otherwhen said contact arm is in said latched position to cause disengagementof said latch and said contact arm, means operable upon disengagement ofsaid contact arm and said latch for moving said contact arm from saidlatched position to an unlatched position, said operating abutment onsaid contact arm lying in the path of movement of said cam surface andout of the path of movement of said operating surface when said contactarm is in said latched position and lying in the path of movement ofsaid operating surface when said contact member is in said unlatchedposition.

4. A circuit breaker comprising a vertically and horizontally movablecontact member and a rectilinearly reciprocable handle member a latchmember adapted to releasably engage a portion of said contact member,said handle member having a cam surface thereon engageable with saidcontact member for slidably moving said contact member in a directiontransverse to the path of movement of said rectilinearly movable handlemember and out of engagement with said latch member, means biasing saidhandle member to move said cam surface away from engagement with saidcontact member and means carried by said handle member engageable withsaid contact member for limiting said movement of said handle member.

5. An electric circuit breaker comprising a manually operable memberhaving a cam surface and as operating surface, said manually operablemember being mounted for reciprocating straight-line movement, a movablecontact member having an operating abutment, said movable contact memberbeing movable in a direction generally parallel to said movement of saidmanually operable member and said movable contact member also beingmovable in a direction generally transverse to said path of movement ofsaid manually operable member, said cam surface of said manuallyoperable member being operable to move said movable contact member insaid generally transverse direction and said operating surface beingoperable to move said movable contact member in said generally paralleldirection, biasing means biasing said movable contact member againstmovement in both of said directions, movement limiting means forlimiting said transverse and said parallel movement of said contactmember to hold said contact member in latched position with saidabutment in the path of movement of said cam surface and out of the pathof movement of said operating surface, and means for releasing at leasta portion of said limiting means to permit movement of said movablecontact member under the influence of said biasing means to an unlatchedposition in which said abutment is in the path of movement of saidoperating surface.

6. An electric circuit breaker comprising a manually operable member, amovable contact member, said'manuall'y operable member being mounted forreciprocating straight-line movement ina predetermined path, saidmovable contact member being movable in a first directiongenerallyparallel to said path of movement of said manually operablemember and also movable in a direction generally transverse to said pathof movement of said manually operable member, first stop means forlimiting said transverse movement of said movable contact member, secondstop means. for limiting said parallel movement of "said'movable contactmember, acam surface on said manually operable member for moving saidmovable contact member in said transverse direction, an operatingsurface on saidmanually operable member for moving said movable contactmember in said parallel direction, said transverse stop means beingpositioned so as to prevent'engagement of :saidoperating surface of saidmanually operable member with said contact member so long as saidimovable contact member is in contact with said transverse stop meansand biasing means for moving said movable contact member when releasedfrom said transverse .stop means to a positionwhere said operatingsurface can engage said movable contact member.

7. An electric, circuit breaker comprising a reciprocable manuallyoperable member, a movable. contact member extending, generallytransverse to the path of movement of said'manually" operable member,said movable contact member having a contact-carrying portion at one endand a latch'portion at the other end and an intermediate operatingportion, biasing means biasing said movable contact member parallel tosaid path of movement in a circuit-closed direction, latch means forrestricting movement of said'latchportion of said movable contact memberinsaid circuit-closed direction, relatively stationary contactmeans for.limiting the travel of said contactcarrying portion of, said manuallymovablecontact portiOninsai-d closed-circuit direction, said biasingmeans operating on said movable. contact member adjacent saidintermediate portion, biasing means biasing said movable contact member.transversely to said path of movement of said manually operable member,stop means limiting such transverse movement of said movable contactmember whenin engagement with said movable latch member and cam meanscarried by said manually operable member for camming saidmovable contactmember transversely out of engagement with said latch member.

8. An electric circuit breaker comprising a casing, a firstcontact, asecond contact movable relative to said first contact between open andclosed circuit positions, an M operating. arm for said second contact,said operating arm having a. contact operating portion at one endthereof, a retainingledgenormally stationary with respect to saidcasingiand adaptedto normally engage the other end of saiddoperatingarm, biasing meansbiasingsaid one end of, saidoperating arm towardcontact-making position andbiasing saidotherendof said contact armagainst said ledge, manually. operable means for sliding said contactoperating arm away-from and out of engagement with saidledge while.saidledgeremains stationary, an abutment on said manually operablemeans, said biasing means rotating. said contact operating arm aboutsaid abutment to open-circuit condition upon release of said operatingarm from said ledge.

9. An electric circuitbreaker comprisinga first cone operable handlemeans having a cam surface for slidtact, a second contact movablerelative to said first contact between openandcl-osedrcircuit positions,an elongated contact operating member for operating said relativelymovable contact, said elongated contact operating member carrying saidmovable contact at one end thereof and having a latch surface at theother end thereof, latch means carried by saidIinsulating casing fornormally engagingand restraining said latch surface of said contactoperating member, spring means biasing said movable contact operatingmember and said movable contact toward said stationary contact andbiasing said latch surface,

against said latch retainingmeans, andfmanually operable meansengageable with said elongated contact operating;

member and operable to slide said contact member longitudinally awayfrom said' latch retainingsurface toward said rel atively stationarycontact, a pivot abutmenton said manually operable member, said biasingmeans being adapted to rotate said contact operating member about saidpivot abutment upon release of said contact member from said latchsurface to an open-circuit position.

16. electric circuit. breaker comprising an insulating casing, a firstcontact, a second contact movable relative to said first contact, anelongated contact member carrying said movablecontact'at one end thereofand having a pivot centrally thereof, a releasable latch surface at theother end of said contact member, latchretaining means, biasing meansbiasing said contact member into engagement with" saidrelatlvely'stationary" ciprocating fashion along a rectilinear pathextendinggenerally transverse to said elongated contact member.- 12. Anelectric switching device comprising a casing of insulating material, afirst contact mounted in said casing, a, second contact movablerelativev to said first contact, contact operating meansfor operatingsaid'mov able contact between open andclosed circuit positions;

said contact operating means comprising an elongated contact armcarrying said movable contact adjacent one end thereof and having alatch surface adjacent the other end thereof, said contact arm having anoperating portion intermediate its said ends, biasing means urging saidcontact arm toward said relatively stationary contact and latchretaining means carried by said insulating casing for normallyrestraining said latch portion of said contact arm, manually operablemeans for operating said contact member between open and closed circuitpositions, said biasing being adapted to rotate said movable contact armabout a portion of said manually operable memberso asto move saidvmovable contact away from said relatively stationary contact to an. opencircuit position when said latch surface is released from said latchretaining means, and a cam surface on said manually operable member forengaging said oper: ating surface of said contact arm for sliding saidcontact arm longitudinally out of engagement with said latch retainingsurface;

I 13. An electric. circuit breaker comprising a casing of insulatingmaterial, a first contact, an elongated contact arm carrying a secondcontact adjacent one end thereof' and having a latch surface adjacentthe other end thereof and an operating portion intermediate the saidends, latch retaining means, biasing means urging said contact arm intoengagement with said relativelyvstationary contact and against saidlatch retaining means, manually ing said movable contact member outofengagement with said latch retaining means, said biasing means servingto rotate said contact arm about a portion of said manually operablemeans upon release of said latch from said latch retaining means, saidmanually operable handle being movable to a position where said camsurface is. out of engagement with said operating portion of said,

contact member, biasing means for moving said contact member upondisengagement of said cam surface 9 from said operating portion to aposition wherein it lies in the path of movement of a substantiallydifferent portion of said manually operable member.

References Cited in the file of this patent 5 UNITED STATES PATENTS Re.22,218 Von Hoorn Nov. 3, 1942 2,076,385 Petersen Apr. 6, 1937 2,132,627Jackson Oct. 11, 1938 10 2,150,012 Von Hoorn Mar. 7, 1939 2,156,762Jackson et al May 2, 1939 10 Jennings Jan. 21, 1941 Von Hoorn Feb. 25,1941 Frank et a1. June 1, 1943 Platz May 1, 1945 Jackson Jan. 12, 1954Cellerini et a1. Nov. 2, 1954 Jackson et al. Dec. 14, 1954 FOREIGNPATENTS Great Britain Dec. 1, 1954

